Advanced flash memory technology and trends for file storage application

This paper describes a high density Flash memory technology suitable for file storage application. Requirements for file storage memory are low cost, high speed programming and erasing, low power consumption and good endurance characteristics. In order to satisfy these requirements, key technologies of Self-Aligned STI (SA-STI) cell, uniform FN-FN program/erase scheme and Multi-level-cell (MLC) technology have been developed[1,2,3]. By using SA-STI technology, small cell size of 4F(2) (F; Feature size) can be realized. Reliable tunnel oxide can be also obtained[3] because the floating gate does not overlap the STI corner. As a result, reliable 512Mbit Flash memories with 0.145um(2) cell size under 0.175um design rule have been newly developed based on these technologies, as well as 0.25um 256Mbit[4]. Moreover, MLC technology combined with this small cell size of 4F(2) can reduce bit cost more, and will be able to expand file storage market in the near future.